This invention relates to implantable devices which can be infused with fluid for promoting tissue growth or tissue expansion, and more particularly to a flexible, foldable, fluid expandable prosthetic device that can be directly infused by a needle and is self sealing when the needle is removed.
The promotion of tissue growth or tissue expansion, as for example, in a mammary prosthesis, is generally based on a gradual accumulation of fluid in an expansible fluid containing device or prosthesis. The prosthesis is typically a collapsible shell formed of a flexible, foldable material which establishes a fluid chamber. Periodic infusions of fluid are made into the fluid chamber to develop a gradual expansion of the surrounding shell. As a result of such periodic infusions of fluid, the tissue which overlies the prosthesis expands or grows accordingly.
Infusion of fluid into a tissue expander prosthesis is normally accomplished with an infusion needle. Since a tissue expander shell is likely to leak if punctured by a needle, it is common practice to infuse fluid at a location that is remote from the tissue expander shell. A tissue expander system thus generally includes a remote needle penetrable septum such as shown in U.S. Pat. Nos. 4,190,040; 4,463,733; 4,543,088 and 4,685,447.
Septums are relatively inflexible, non-expandable, hollow structures that have a needle access portion to receive a fluid infusing needle. Septums enable fluid to flow into a tissue expander structure once the inner capacity of the septum is filled. As shown in the foregoing patents, the septum is connected to a tissue expander structure by a conduit such that fluid infused into the septum is directed by the conduit into a fluid entry port of the tissue expander chamber. The term "fluid entry port" as used herein refers to a predetermined fluid inlet opening in a tissue expander chamber to which a fluid conduit is connected.
The needle access portion of a septum usually has the capability of being resealable when an injection needle is withdrawn. The combination of a septum and a conduit for infusing fluid into a tissue expander chamber can also be used to remove fluid from the chamber.
Known tissue expansion systems often require that the septum and the conduit that connects the septum to the tissue expander prosthesis be implanted with the tissue expander prosthesis. The surgery for implanting a tissue expansion system normally includes an incision or incisions through which the implant is directed and a surgical pocket for accommodating the implant. The size of the implantation incision and pocket is generally based upon the size of the respective components of the tissue expander system. Thus a tissue expander with a septum requires a greater amount of surgery to implant than a tissue expander without a septum.
Ordinarily, the needle access portion of a septum is of substantially less size than the tissue expansion chamber and represents a relatively small target area in which to insert a needle for infusing or withdrawing fluid. Since repetitive infusions of fluid are usually required to accumulate fluid in a tissue expander chamber and accomplish a desired tissue expansion, the skin in the area of the septum often becomes sensitized due to frequent penetrations by an infusion needle in a relatively small needle penetration area. In addition, a septum can migrate from its original implant location which can lead to infusion problems. In some instances a septum will undesirably overturn making it difficult or impossible to carry out infusion. Surgical correction may thus be required for migration and overturning problems.
It is thus desirable to provide a tissue expansion device suitable for use as a mammary prosthesis and as a prosthesis in other areas of the body that does not require a septum or fluid conduit for the intake or removal of fluid, is self sealing, has a relatively large area for insertion of an infusion needle and can be implanted with a relatively small surgical incision.